


The Last Piece of the Puzzle

by therealfroggy



Category: Chuck (TV)
Genre: Multi, Threesome - F/M/M
Language: English
Status: Completed
Published: 2020-05-24
Updated: 2020-05-24
Packaged: 2021-03-03 05:26:49
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,602
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24359536
Author URL: https://archiveofourown.org/users/therealfroggy/pseuds/therealfroggy
Summary: Post-series. Chuck and Sarah are married, happily, and they love each other, of course they do. It's just that there's something missing.Someone.Established Chuck/Sarah turning into Chuck/Sarah/Casey.
Relationships: Chuck Bartowski/John Casey/Sarah Walker
Kudos: 28





	The Last Piece of the Puzzle

It all comes together when Sarah moans the wrong name during sex.

They have both known, for some time, that something is wrong, but neither of them have known how to say it out loud. That something is missing. It doesn't surprise Chuck that they haven't figured it out earlier, or that they haven't revealed it to each other; their life together doesn't have any obvious issues. They are young and attractive, their work is exciting, the sex is good. They have it all.

Except that missing piece.

Sarah is on her hands and knees, and Chuck has his hand fisted in her hair, kneeling behind her, taking her roughly. Sarah said earlier that she wanted it hard, rough, that she wanted bruises. They haven't done that before but Chuck is game; it's almost close enough to the roughness he craves himself. So he pulls on those blonde locks and treats her like a thing, like something for him to fuck, rather than the woman he loves so much.

And then she moans, really moans, and it's the wrong name. No, Chuck thinks, it's the right name; it's the name they've both been thinking about for months now. Ever since they both found out something is missing. Since they realised nothing is the same without that last piece.

“You want him?” Chuck pants, and just saying it excites him. “You wish it was him fucking you, his cock in you like this?”

Sarah cries out and comes around him, her body rippling around Chuck's own hard cock.

“Chuck, I didn't mean -” Sarah begins breathlessly, but Chuck resumes his thrusts.

“Oh, you did. I do, too, Sarah; I wish... I wish he was here with us.”

And imagining just that, Chuck comes, too.

They lie there staring at each other afterwards.

“We need him back, don't we?” Chuck asks softly.

“He was never ours,” Sarah says, and her eyes are sad. “I mean, not like this. I don't think he... he would.”

Chuck kisses her. “I love you. But I think we both need something more.”

Sarah smiles. “You always knew me better than I did. It's not that I don't love you, Chuck...”

“It's just that we're not complete like this,” Chuck says soothingly. “You don't have to explain. I know. You think we could persuade him to at least try?”

Sarah grows pensive. “I... I think so. If we both... I mean, I don't know which he'd prefer.”

Chuck snorts. “I don't think I ever stood much of a chance with him, Sarah.”

“Maybe not at first, but the way he looked at you just before he left...” she says, and her eyes light up with excitement. “God, I used to imagine it. To see you two together, think about what that would look like. Maybe he would.”

“If he doesn't, I'm okay with you having him, as long as I can watch,” Chuck says, but he knows it's not true. He knows if Sarah gets a taste of what they both want so badly, she'll never be entirely his again. He knows it's all or nothing; if they can't both share it, they'll fall apart.

“I'll call him tomorrow,” Sarah says, and she slides into Chuck's arms. “I'll ask him to dinner. We'll buy scotch, we'll offer him everything. If there's any chance...”

“He'll come over, we'll get him to relax,” Chuck agrees, responding to the image she's painting. “You start; it'll be less of a shock. You ease him into the idea, and when he's ready, we... we'll make sure he sees what's missing from this.”

Sarah's eyes are dark blue with lust. It's mere minutes before they're both coming, both of them moaning this time.

***

Four nights later, dinner is on the table, a bottle of wine is breathing on the counter, and just the right brand of bourbon is placed in plain sight so it'll be obvious it's there to be drunk. Sarah is in one of her dresses; a blue one that leaves only barely enough to the imagination and leaves little trails of fire in Chuck's blood. Chuck let her pick out his outfit; he's wearing suit slacks and a short-sleeved shirt that Sarah thinks shows him to his best advantage.

Chuck still doesn't think he'll get anywhere with their guest, but Sarah is adamant that they'll share this, just like they share everything else in their life. Chuck knows he's not strong enough to refuse her anything, even if it means the end of them.

Because if Chuck has to see her with him, with their missing piece, and not be welcome to join them, then he'll have to jump off a bridge before their roast gets cold.

The doorbell rings and Chuck takes a deep breath, then goes to open it.

“Here goes,” he tells Sarah quietly as he passes her. She's putting on one last coat of lipstick.

Chuck exhales slowly and opens the door. “Hey, Casey! Come on in!”

The former agent allows himself a tiny smile. “Bartowski. Good to see you. Here.”

He holds out a platter of mini quiches, and Chuck laughs. Good times, good times. Chuck gestures for Casey to come in, and then Sarah is there, subjecting Casey to her entire radiant self.

“Casey, hi. It's been a while. What have you been up to?”

They start talking shop, then personal. Chuck pours them all wine, they eat the quiches while waiting for the roast, and it's like only days instead of months have passed since the last time they saw each other. Casey even chuckles, and Sarah leans in and places a hand on his arm.

Then Casey's eyes go wide and he backs up. “Uh, maybe I'll just... Excuse me.”

And he disappears in the direction of their bathroom.

Sarah frowns. “Go after him, Chuck. He saw my move and freaked.”

Chuck wouldn't call it freaking, but he does as he's told while Sarah takes the roast out of the oven. When he knocks on the door, he can hear the water running inside.

“Casey? You okay, buddy?”

The water shuts off, and Casey opens the door. His face is wet and it's obvious he just splashed his face with cold water. Wow. That's really demonstrative, for Casey.

“Casey?”

“Bartowski, I... I don't want to have to tell you this,” Casey says gruffly, and Chuck has never seen him uncomfortable like this. “But Walker...”

Which is when it hits Chuck that Casey thinks Sarah is trying to cheat on him. He thinks her spy seduction tricks have escaped Chuck's notice. And Casey, the all-American hero, is too much of a hero to let that slide.

The nerd – for something of a nerd he will always be, regardless of how far he has come – grins widely at Casey. Who is just too decent for his own good, apparently. “What, you're not interested? Not even with her in that dress?”

Casey's whole face recoils. “Chuck, she's your wife!”

“But if she wasn't? Or... or if I was fine with it?” Chuck says carefully, watching Casey for signs of disaster. This was not how they had planned it, but if Casey is comfortable enough with Chuck for this conversation...

The other man goes deadly still.

“I... I'm fine with it, Casey. For you. If the two people I care about most in the world wanted to... wanted that, then I wouldn't object,” Chuck says, taking a tentative step closer to the older man. Feelings have always been his forte, and it's clearly time to play to his strengths.

“For me,” Casey repeats quietly, looking directly into Chuck's eyes. “You mean... You're saying that if you can't have me, at least she can.”

It makes Chuck's heart sink to hear it, but he nods. “Yeah. We both want you. It's just not right without you. You're the missing piece. But you don't swing this way, right? That's fine. If I can... watch. Just don't shut me out.”

Casey turns around abruptly, smacking a hand against the wall. “Dammit, Bartowski!”

Chuck jolts with the intensity in that voice. He doesn't dare move.

“Stop selling yourself short!” Casey barks, and he suddenly fists a hand in Chuck's collar. “You'd give up your marriage so she can have what she wants, but what about you? Don't you want something?”

Chuck shudders just from the proximity to the man he's wanted for so long. It's so intense. “Of course I do. But anything is better than nothing.”

That's when Casey crashes their lips together so violently Chuck feels his teeth scrape against something tender.

“God dammit, Bartowski, always with the self-sacrifice. Always putting others before yourself. Always making it so fucking difficult to turn away from you.”

Chuck's mind is moving too slowly and he can't keep up with what Casey is saying.

“You think you're the only one who wants? Who sacrifices? Being a spy is a fucking drag sometimes, Bartowski, and you know what the worst part is?” Casey demands angrily.

Chuck mutely shakes his head.

“It's finding out that if you hadn't been so fucking _noble_ , and just taken what you wanted for once, apparently I could have been getting laid instead of living like a fucking monk since you left,” the big agent growls.

At this, Chuck regains the power of speech. “Hey! You were the one who left!”

“Boys.”

It's Sarah's cool voice, and it pulls them both up short. Chuck turns to look down the narrow passage at her, and wow, she got naked really fast. From his controlled intake of air, it would appear Casey approves.

“How about, instead of arguing over who left first, we start making up for lost time?” Sarah says, and she's smiling at them, her spy smile, her seduction smile. So naked.

“Walker, I -”

“No, don't explain, it's fine,” Sarah says, and her smile is warmer than her voice. “We want you here with us. We want _you_. If you want us, then just stay. It's as simple as that, at least for tonight.”

Casey looks torn, his handsome face showing his indecision. Chuck moves closer to him, still a little shell-shocked by the kiss. Then Sarah is coming towards them, and it's impossible not to watch her breasts sway gently as she walks.

“Stay, Casey,” Chuck mutters, slowly putting a hand on the other man's arm. “It's not right without you.”

“You're... both...”

Casey doesn't seem to know where to go from here, so Chuck takes over. He puts one hand on the man's shoulder and steers him into their bedroom, where they put everything in order earlier. Sarah slides her golden-skinned, gorgeous body onto their huge bed, and hunger lights up Casey's eyes.

“I shouldn't.”

“Doesn't matter,” Chuck says quietly. “She wants you so bad, Casey, you need to give her what she wants. We'll let you have anything you want, too.”

Sarah holds out her arms. “Please.”

John Casey groans, covering his eyes with one big hand. “You're not... This won't last. It can't.”

“Months, John. We've been thinking about you for months. Like this, in bed, with each other,” Chuck says, slowly reaching for the buttons on Casey's shirt. “She wants you. I want you. We'll give you everything, we'll give you your own room here if you want it! Please, just give it a shot.”

“You'll make it worth my while, huh?” Casey snorts, then raises his head to look at Chuck. “Chuck?”

“Yes,” Chuck says simply, leaning in slowly. “Can I kiss you?”

Casey doesn't wait for another second before surging forwards until their lips are pressed together again, gentler this time but no less desperate. They get most of their clothes off, then Chuck pushes them apart and gasps for air.

“Sarah, she -”

“Walker,” Casey begins slowly, turning to face her. “I... I want it. You sure?”

“Partners, John. I never stopped feeling like that. Come here,” she replies softly, shifting further up on the bed, leaning against the pillows. When she moves her legs they can see glimpses of dark pink flesh, dusted with trimmed blonde hair, and Chuck's mouth goes dry. She looks at Casey and smiles. “Let me show you.”

When Casey goes to her – kneels on the bed and starts crawling slowly over her – Chuck watches the play of muscle across that broad back with barely restrained desperation. The contrast between them bewitches him; Sarah is smaller and softer and curvier than she looks with clothes on, and Casey is all hard muscle and solid presence. She's fair, he's dark.

They're both so perfect, and Chuck finds himself just wanting to watch for a moment, afraid to miss anything.

“John,” Sarah purrs, sliding her hands up around his neck. “What do you like?”

Casey leans down and kisses her, a lot gentler than he kissed Chuck, a classic movie ending kiss. Chuck is almost jealous on behalf of Sarah, because the pure desperation he tasted on the other man's tongue is not something you just forget, and he wishes she could have had that. But then Casey is backing down, trailing bites down Sarah's body, and Chuck wishes it were him lying there.

“I want all of it,” Casey mutters, his lips brushing against Sarah's belly. She wriggles; she's ticklish there. “Both of you. However you... No, I want it like you do it. I want to feel what you feel.”

“Taste her,” Chuck urges, following Casey onto the bed. He kneels beside them. “Put your mouth on her, John, I'll tell you what she likes.”

Sarah spreads her legs wide and Casey's broad shoulders press them even further apart. The big agent is panting, his eyes wide and dark, and he lowers his head and just presses his face against her, nuzzling into that delicate flesh.

Sarah arches into it. “John!”

Chuck leans in until he can smell them both, Sarah's musk and Casey's cologne. He puts his mouth on Casey's shoulder and kisses his way across to the man's neck, then licks down along his spine. Casey goes tense, but then does something which makes Sarah moan, so Chuck just continues. There's no more room on the bed, so he drops to the floor, gets to his knees and gets in between Casey's legs.

“This okay?” Chuck asks, pausing, hands stroking slowly up Casey's thighs.

“Bartowski, I...” Casey starts, but he doesn't finish it.

“Anything you want, John, but nothing else,” Chuck assures him. “Do you like this?”

“Don't know,” is Casey's gruff reply. “I never... Not this.”

Chuck puts his hands on Casey's ass, and the other man tenses, but the movement of his head tells Chuck he's still pleasuring Sarah, so the nerd palms him open and leans in to breathe over that forbidden territory. Casey grunts – this is a new one, one Chuck hasn't heard before – and lifts his hips slightly.

Chuck licks him there, slowly and gently. Casey doesn't move, so Chuck does it again, harder this time. Casey groans, and Sarah makes an answering sound; Chuck knows she likes it when you growl against her like that. He puts his tongue on Casey and gives it his best.

“Bartowski,” Casey gasps, then does something to make Sarah hiss. “Bartowski, I want to feel what she's feeling. When you fuck her.”

Chuck loses track for a moment, but quickly recovers. He tilts his head a little, dips it lower to suck at the tender skin just behind Casey's balls, and the agent gives a muffled shout. Fuck Casey. He was just told he would be allowed to fuck Casey. Hasn't he craved it? Hasn't he wanted this like nothing else?

“Make her come,” Chuck says, mutters, against Casey's inner thigh. “Make her come, and I'll fuck you.”

Casey growls his agreement and pushes his face against Sarah's wetness. She mewls happily and bucks her hips against his face, and Chuck lifts his head for a moment to watch as Casey really goes in for the kill. The agent's big hands are underneath Sarah's ass, lifting her hips to meet his face, and those broad shoulders are flexing minutely as he works on her.

Sarah gives that small sob that lets Chuck know she's close.

“John, bite her,” Chuck says eagerly. “Bite her, then suck hard on her clit.”

Casey does, and Sarah comes; she comes screaming. It's a good thing they don't really have neighbours, because the sounds she's making are obscene. Casey groans again and really goes after her; he tilts his head and presses in even closer, making Sarah buck and writhe through her orgasm.

“Oh, John, look at her,” Chuck says breathlessly, moving up so he can see them both. “Look at what you do to her.”

Casey lifts his head to look back at Chuck, the NSA agent's face wet with her juices. Chuck leans in and licks them off Casey's chin; the familiar taste of Sarah rolls over his tongue along with the maleness of Casey. Then Casey, albeit hesitantly, opens his mouth and kisses Chuck.

“I just -” Chuck begins, almost laughing, but Casey silences him with another kiss.

“I never had you pegged for the kinky sort, Bartowski,” Casey says, but it's _his_ eyes that are clouded over and _his_ body that's shaking with need. Chuck wonders how long he's been single, or at least, been celibate.

“Go on, fuck her,” Chuck suggests, nodding towards Sarah. She's breathing hard, body heaving with it. “Feel what I feel.”

Casey turns to Sarah, the two of them locking blue eyes like mirroring images of need.

“Walker?”

“Come on, I want it,” she insists, reaching up for him. “I've wanted it for so long.”

Casey slowly crawls back up, then looks over his shoulder to meet Chuck's eyes. It's Chuck's hand that slips underneath that sturdy body and grasps a painfully hard cock, that holds it steady for Sarah. Casey has surrendered to them completely; he's letting himself be guided and moved by their hands and bodies. He looks barely sane; his eyes are unfocused and his mouth is moving without words.

“Chuck,” Sarah gasps, her head thrown back. “Chuck, oh God, he's so hard!”

“Walker,” Casey breathes, “so wet, so... so _tight_.”

Chuck's eyes roll back in his head. These two people, the two people he loves most, are too much for him. Too sexy, too obscene together, too intense for a nerd like him. But they're here, they're his, he needs to step up. So without taking his eyes off them, he reaches into the nightstand drawer and fumbles around for the lube and condoms.

“I'm going to fuck you, John,” Chuck says, and just saying the words makes him leak precome like he was fourteen again. “Let you feel everything we're feeling, all at the same time.”

Casey stills. “Do it. Hurry up, Bartowski, do it.”

Chuck rolls the condom on with shaking hands, then pops the cap on the tube of lube and coats his fingers. “Don't move. Sarah, you okay?”

Sarah sighs. “Perfect.”

Chuck slips his fingers back between Casey's ass cheeks and the gruff agent tenses up all over. The muscle under his fingers is clenched tightly, so Chuck rubs it gently with slick digits until Casey lets out a breath and leans down to kiss Sarah's neck.

“Kiss me, John,” Sarah pleads.

While Casey and Sarah start kissing, messily and loudly, Chuck pushes a finger gently into Casey. He can do this; he's done it for Sarah, he knows how to take it slow. Casey doesn't really seem like the type for slow and gentle, but Chuck is still a little concerned that the agent will bolt if they make any sudden moves.

Casey is so hot inside.

Chuck prepares him as thoroughly as he can, and then Casey starts breathing heavily against Sarah's neck and pushing his hips back to meet Chuck's. The older man seems restless, impatient. Chuck daringly leans in to kiss the small of Casey's back, then stills his hand.

“Ready?”

“Go for it,” Casey demands. “Come on, get on with it.”

Chuck grins despite the tension and leans up to find the right position. He finds Casey's entrance and pushes, slides, loses himself in the deep, slick glide into the other man's body. It's tighter than Sarah, hotter, too. It feels more dangerous.

“Tell me,” Sarah begs, and Chuck draws a deep breath.

“He's amazing,” Chuck breathes, and uses his hips to push Casey forwards into Sarah. “Feels amazing. John, you okay?”

“Keep going,” Casey grunts, fisting the sheets to either side of Sarah's ribcage. He's so big, so wide, so massive compared to her. But Chuck is just as tall and he's got a good grip of Casey's hip, and he controls their deep, slow thrusts. Casey's panting, Sarah looking up at him with those eyes, and Chuck is about to lose his mind to how amazing this is.

“Think you can come like this?” Chuck breathes into the other man's ear. “Think we can get you off between us?”

“Shut up or this will be over way too fast,” is the growled reply.

Sarah arches up and grins at them. “You should see his face, Chuck. He loves this.”

“Let's make him love it even more,” Chuck grins back over Casey's shoulder. He keeps thrusting, slow and deep, moving Casey with him. “Sarah, can you...?”

From the way Casey groans and clenches around him, Chuck can tell she did that thing she does where her body tightens _all over_ and it usually takes everything in him not to come the moment she does it. Casey is stubborn, though; still holding on, still refusing himself release. Chuck reaches around to put a hand on Casey's broad chest, scratching lightly across it with his fingernails.

“John, just let go,” he coaxes, thrusts never ceasing or slowing. “Want you to. She wants you to. Show us you want this.”

Casey's shudder rocks them both. “Chuck... I -”

Sarah does that thing again and this time, Casey gives in. He moans, deep and helpless, and bucks between them, shaking with orgasm. Sarah reaches greedy hands up for him and pulls him down, and Chuck lets him go, lets Casey sink down on top of his wife to nuzzle gently at her ear.

They're indescribably beautiful to him in that moment.

“Wow,” Chuck comments. It's all he can manage at the moment.

“Bartowski,” Casey grunts, barely audible from where his lips are mashed against Sarah's clavicle, “get it over with. I need to be able to walk tomorrow.”

Chuck laughs. “No, you don't. We were thinking brunch in bed and then more sex. No walking required.”

“Stop teasing,” Sarah says warmly, running her small hands over Casey's ridiculously wide shoulders. She sounds a little breathless under all that weight. “Come on, honey, you've waited long enough.”

“Mm,” Casey agrees, his mouth now moving down towards Sarah's breasts. “Go for it.”

So Chuck stops trying to focus and just lets himself feel it. He leans forwards, hands planted next to Casey's, and snaps his hips forwards. Casey moans a little and Sarah's eyes go dark, focusing on Chuck's face. He thrusts faster, chasing orgasms and marvelling in the feeling of his former handler underneath him.

“Casey,” he moans, feeling heat curling at the base of his spine. “Casey, can I...”

“Yes,” the agent rumbles, and Chuck feels orgasm overtake him. With a shout, he fucks forward into that broad body again and again, heat rushing through him until he collapses, spent, against Casey's back.

“Boys,” Sarah gasps, “move!”

Chuck pulls out, gently, then flops to the side. Casey backs up, gets to his knees and seems uncertain where to go from there, so Sarah and Chuck scoot sideways just far enough to make space between them.

“Here, John. Stay,” Sarah suggests, patting the bed.

“Shouldn't you maybe...” Casey begins, but Chuck leans up and grabs his hand.

“C'mere. We'll take turns being the filling in the sandwich.”

Sarah giggles. Casey scowls a little, but in a good-natured way, then settles between them, lying a little stiffly. Chuck leans in and kisses his way across his chest until he meets Sarah, who's had the same idea, halfway. They kiss right over Casey's heart, and Chuck loves his wife so much it feels like he's going to explode from it.

“I love you,” he says, smiling at her, then looks down at Casey. “You, too. I love you and you. Both of you.”

Sarah smiles beatifically and gives him a little peck on the lips, then leans down to kiss Casey again. “Me, too.”

Casey just lies there, looking shell-shocked, and lets himself be kissed. Hesitantly, he slides a hand up Sarah's smooth back and lifts another hand to reach for Chuck. That big, broad hand slides into Chuck's hair and the younger man loves how it feels to have his hair fisted by someone bigger than him. He totally understands why Sarah likes this.

“So... that happened,” Casey comments intelligently.

Chuck laughs. Sarah snuggles up against Casey. “Give us half an hour and it can happen again.”

Casey grins a little, hesitantly. He so rarely smiles that it feels like a jolt to the system when it happens. A hot, sweet jolt right at the core of them.

“No, seriously, John, we weren't kidding before. We've both thought about this for months before we talked about it. This feels right,” Chuck says. “We'd like you to stay. We understand if you don't want to, but... Our casa, etcetera.”

“We missed you,” Sarah says softly, and she and Chuck lace their fingers together right on top of Casey's chest. “It was always the three of us against the world.”

“I'll, uh... stay the night, then,” Casey says gruffly. “If that's okay with you.”

“That's always gonna be okay with us,” Chuck assures him. “Hey, you want some more wine? I feel like we should have some more wine.”

“I'll take some of that bourbon if you're offering,” Casey says, and his cheeks are a little red. “You got that special, huh?”

“Our clever seduction bourbon,” Chuck confirms. “I mean, I don't really drink that stuff, so I guess you're going to have to hang around at least until the bottle's empty, huh?”

Casey snorts a laugh. “Classy, Bartowski. Real classy.”

“How about we all put some robes on and we can have some dinner?” Sarah suggests, sitting up. “I don't know about you, but I'm starving.”

The two men follow suit. Wrapped in bathrobes (Chuck has to use one of Sarah's because Casey can't fit in any but Chuck's only robe, and he looks ridiculous in pink satin), they skip the dining table in favour of just fixing plates and eating them on the couch. They have more wine, Casey breaks into the bourbon and soon becomes a lot more mellow, and by the end of the meal, they're all collapsed together on the couch, sleepy and sated.

“I guess our clever seduction scheme worked out perfectly,” Chuck says, one hand rubbing idle circles on Sarah's thigh and the other resting quietly on Casey's.

“I guess it did,” Casey agrees. “When someone finally turned that seduction school crap into a useful skill set, I guess it had to be you two.”

“Well, you know how it is, it's always easier to complete a mission when someone has your back,” Sarah adds with a smile. “And speaking of, how would you boys feel about me being in the middle next time?”

Chuck grins happily. “I think we can manage that.”

And it turns out they absolutely can.


End file.
